Shop Ronni Simon Designs › Black Onyx, Hematite & Labradorite Knotted Necklace Image 1 of 2 Image 2 of 2 Black Onyx, Hematite & Labradorite Knotted Necklace Sale Price: $135.00 Original Price: $195.00 40” continuous strand of 8-25mm gemstones knotted on black silk thread. Add To Cart Added! 40” continuous strand of 8-25mm gemstones knotted on black silk thread.